An empirical study on renegotiated CBR for VBR video services based on network testbed

For multimedia network services, bandwidth reservation levels for video transmissions are conventionally defined using traffic descriptors that remain static over the entire playback duration of the video transmissions. Aimed at addressing the bandwidth wastefulness of using the static reservation, renegotiated Constant-Bit-Rate (RCBR) mechanism has been proposed to perform dynamic bandwidth allocation with periodical bandwidth renegotiation during any multimedia transmission sessions. However, this mechanism has been only examined via simulations and theoretical analysis previously. In this study, we have conducted rigorous empirical studies on RCBR scheme using a real network testbed to study its performance. Our study reveals interesting results and provides new insight to any practical deployment of RCBR mechanism and service over broadband packet networks. Moreover, a smoothing technique at application layer is proposed and evaluated in RCBR context to maximize the efficiency of RCBR scheme. We present empirical results and analysis, and highlight our observations.